Aluminum and chromium and zirconium alloy



Patented Aug. 20,

UNITED STATES ALUDIINUM AND CHROMIUM AND ZIRCONIUM ALLOY Henry L. Coles,Boulder, 0010., assignor to William Sokolec, Chicago, Ill.

No Drawing. Application July 14, 1938,

Serial No. 219,156

6 Claims.

This invention pertains to an improved alloy and to a type of improvedproduct made therefrom.

\ The novel alloy herein relates to alloys in which aluminum is presentas a major constituent, and the preferred type of product is a cookingutensil.

Further, the novel alloy relates to aluminumchromium-zirconium alloysand to products made therefrom that have shown a very marked in: creasein corrosion-resistance, and toughness; and ability to be fabricatedwithout deteriorating. Certain alloys and products made from thosealloys have been placed on the market with assertions as to certaincharacteristics and abilities. It has been found, however, that theassertions have not been fulfilled. For instance, some of the productsare represented as being noncorrosive, but it is found that theydiscolor, which is one form of corrosion, and that they pit and receiveimpurities in the pit holes and consequently are not desirable for manyuses, especially for cooking utensils.

One of the features of this invention is to provide a new alloy and animproved product therefrom, both of which show a very marked increase inresistance to corrosion, and a particular value in toughness, and whichhave shown that very considerable working or fabrication thereof can becarried on without breaking the alloy or deteriorating the same, thusgiving characteristics and abilities that withstand agreat deal of abusein use without puncturing or bending to such an extent thatdeterioration sets in. In setting forth an example of the inventionherein and of a particular example of a product, a cooking utensil hasbeen selected, for the reason that the alloy and the product meet all ofthe requirements that are required in cooking utensils. The alloy isalso capable of having many and exceptionally large uses in other industries or fields.

In the cooking utensil field or industry, exceptionally high resistanceto corrosion is one of the first requisites, and then the ability to besterilized to become perfectly clean for the storage,

cooking, and serving of food, and then the ability that will continue tobe satisfactory under many 'uses, and the repeatings of those uses, isthat which includes, in its final form, certain amounts of aluminum,chromium, and zirconium.

In the particular example herein of the elements or constituents of thealloy, which gives a most satisfactory alloy and product, chromium ispresent in approximately less than 1 per cent, and zirconium inapproximately less than 1 per cent, and the remainder aluminum. Y Itwill be understood that certain impurities will be'present in trade formbut which are usually considered as negligible.

Certain variations in the alloy have been found to be particularlyvaluable in different compositions. For instance, chromium is found tobe satisfactory in quantities ranging between .60 and .90 per cent. Aparticularly good range of the chromium constituent has been found to bebetween .70 and .80 per cent. One of the best single amounts of chromiumin the alloy is found and .58 per cent, and one of the single desirablepercentages is, approximately .5 per cent. The variations in thechromium and zirconium do, of course, vary the amount of aluminum whichmakes up the remainder of the alloy.

When chromium is present in approximately .75 per cent, and zirconium inapproximately .5 per cent, and the remainder aluminum, the resultingalloy has proven very advantageous, in that a very marked increase inthe corrosionresistance has been noted, and that substantially themaximum toughness of an alloy of these constituents is obtained. Inaddition, the cooking utensil products made from the alloy are readilyformed and fabricated without causing deterioration of the alloy.

In the method of producing the improved alloy and the preferred productit is desirable to alloy the aluminum, chromium and zirconium togetherin the most satisfactory manner to produce the advantageous alloy, andit is found that by melting aluminum 7 and adding thereto chromium oxideand zirconium oxide and allowing the reactions between theseconstituents to automatically take place, that a most satisfactory meltis obtained and poured and rolled, and formed into the final product.

In the preferred method it has been found desirable to make a mixture ofthe chromium oxide and zirconium oxide and then add this mixture to thesurface of the molten aluminum.

' It is helpful to stir the oxide mixture into the molten aluminum atintervals to thus obtain a little more uniformity in'the alloy. Thisstep, however, is not necessary.

As an example of the particular formation of the alloy, and thepreferred product, approximately 100 pounds of aluminum of good purity,99.4 per cent, or better, is melted; about 1% pounds of chromic oxidemixed with about three quarters to one pound of zirconium oxide and thismixture added to the surface of the molten aluminum, and reactionbetween the constituents then takes place to form a definite melt. Thismelt is then poured, but it is desirable to skim the slag therefrom, orto skim substantially all of the slag therefrom. After pouring, themetal is rolled to sheet, plate, or bar form, and is thereafter workedand fabricated, or formed into the particular design of cooking utensildesired.

It will therefore be seen from the foregoing description that a novelcomposition of aluminum, chromium and zirconium has been set forth inwhich there is, approximately, less than 1 per cent chromium, andapproximately less than 1 per cent zirconium, and the remainderaluminum, and from this alloy produce a very advantageous type ofcooking utensil. Such cooking utensils have shown marked resistance tocorrosion, andadaptability to fabrication without deterioration, and tohave exceptional toughness.

Certain modifications and changes may be made in the composition andmethod, but such modifications and changes are desired to be includedWithin scopes of the claims which follow.

I claim:

1. A metallic alloy composed of .60 to .90 per cent chromium, .3 to .6per cent zirconium, and the balance aluminum.

2. A metallic alloy composed of .60 to .90 per cent chromium, .43 to .58per cent zirconium, and the balance aluminum.

3. A metallic alloy composed of .70 to .80 per cent chromium, .43 to .58per cent zirconium, and

the balance aluminum.

4. A metallic alloy composed of .60 to .90 per cent chromium,approximately .5 per cent zirconium and the balance aluminum.

5. A metallic alloy composed of approximately .75 per cent chromium,approximately .5 per cent zirconium, and the balance aluminum.

6. A corrosion-resistant, tough alloy composed of approximately 98.65per cent aluminum, approximately .'75 per cent chromium, andapproximately .6 per cent zirconium.

HENRY L. COLES.

